Emulsion aggregation (EA) toners are used in forming print and/or xerographic images. EA techniques typically involve the formation of an emulsion of resin that have a small particle size of from about 5 to about 500 nanometers in diameter, by heating the resin, optionally with solvent if needed, in water, or by making a emulsion in water using an emulsion polymerization. An optional colorant dispersion, for example of a pigment dispersed in water, optionally with additional resin, is separately formed. The colorant dispersion is added to the emulsion mixture, and an aggregating agent or complexing agent is then added and/or aggregation is otherwise initiated to form aggregated toner particles. The aggregated toner particles are heated to enable coalescence/fusing, thereby achieving aggregated, fused toner particles. United States patents and application publications describing EA toners are well known.
Two main types of EA toners are known. First is an EA process that forms acrylate based, for example, styrene acrylate, toner particles. See U.S. Pat. No. 6,120,967, the entire disclosure of which is incorporated herein by reference, as one example of such a process. Second is an EA process that forms polyester, for example, sodio sulfonated polyester, toner particles. See U.S. Pat. No. 5,916,725, the entire disclosure of which is incorporated herein by reference, as one example of such a process. Alternatively, toner particles can be formed via an EA process that uses preformed polyester emulsions made using solvent flash or phase inversion emulsification (PIE) such as those toner methods described in U.S. Patent Application Publication No. 2008/0236446, the entire disclosure of which is incorporated herein by reference. Additionally, so-called ultra low melt polyester toners can be obtained by incorporation of a suitable crystalline polyester. Examples of EA ultra low melt (ULM) polyester toners, include those described in U.S. Pat. Nos. 5,057,392; 5,147,747; 6,383,705; 6,780,557; 6,942,951; 7,056,635 and U.S. Patent Application Pub. No. 2008/0236446, the disclosures of which are incorporated by reference in their entirety.
Toner blends containing crystalline or semi-crystalline polyester resins with an amorphous resin have been recently shown to provide very desirable ultra low melt fusing, which is important for both high-speed printing and lower fuser power consumption. These types of toners containing crystalline polyesters have been demonstrated suitable for both EA toners, and in conventional jetted toners. Combinations of amorphous and crystalline polyesters may provide toners with relatively low-melting point characteristics, which allows for more energy efficient and faster printing
Currently, ULM polyester based toner products have benchmark crease fix minimum fusing temperature (MFT) of about −20° C. relative to styrene/acrylate EA toners. This improved crease fix MFT performance enables a reduction in fuser energy and enhanced fuser life. The reduction in crease fix MFT is primarily achieved by the introduction of a crystalline polyester resin (about 5 to 10%) into the EA particle design. Although adding more of this crystalline resin does reduce the crease fix MFT even further by about an additional 10° C. (super low melt), conductivity of the crystalline degrades electrical performances of the resulting toner. Accordingly, there is a need to provide a super low melt toner composition. Additionally, there is a need for an EA toner composition with reduced a crease fix MFT of about −30° C. or lower, without sacrificing the electrical performance of the toner.